This project has evolved from the study of hyperactivity in children (now called Attention Deficit Hyperactivity Disorder -- ADHD) through studies of stimulant drugs -dextroamphetamine and caffeine--in children and adults, and now back to studies of drug free ADHD children. In a current study ANS activity and attention has been assessed in 34 boys with diagnoses of Conduct Disorder, Oppositional Defiant Disorder and/or ADHD, the 'Disruptive Behavior Disorders' (DBD) spectrum, selected for their antisocial and disruptive behavior in school and elsewhere, and in 33 normal control boys. We recorded peripheral indicators of ANS activity such as skin conductance (SC), heart rate (HR), and skin temperature during a rest period, presentation of a series of simple tones to which no response is required, and a simple reaction time (RT) task. Attention is assessed by two longer RT tasks which have been used extensively in schizophrenia research: 1) Simple RT with constant and variable preparatory intervals (PI), and 2) Simple, choice, and 'crossmodal' RT to lights and tones. Major results to date show the DBD boys had higher HR but no differences in SC indices of 'arousal'. However they had smaller increases in all baseline measures to the onset of the RT task than controls. There were no differences in ANS responses to nonsignal tones, but the DBD boys gave larger SC responses to the RT stimuli. These results are different from those obtained previously with more 'pure' ADHD samples. RT was slow and variable in the DBD group under all conditions, but particularly slow after long (8 sec) Pls suggesting a specific deficit in sustained attention. The DBD group was also quite impaired in the choice and crossmodal RT paradigms. Thus DBD boys have particular problems when the timing or modality of the stimulus is uncertain. A 2-year clinical followup of these subjects reveals that low ANS baselines are predictive of such outcome variables as institutionalization (HR, SC level), suicide threats (spontaneous SC fluctuations), and suicide attempts (HR).